The invention relates generally to shear spun sub-micrometer fibers and more specifically to shear spun sub-micrometer polymeric fibers.
Polyetherimide (PEI) fibers are used in many applications and composite structures that require various unique properties of the different resins to perform in the necessary environment. Many of these applications require the resins to be in a fiber size much smaller than currently achievable using conventional methods of fiber production at a reasonable throughput rate. This has been a barrier to the introduction and testing of many of these resins suitability for use in these applications. PEI has been converted into fibers using the melt spinning process for some time. Such processes are capable of producing fibers in the range of 10-20 micrometers. Melt blowing has also been attempted with PEI, and there is currently work being done to make this process amenable to using PEI. If the technical hurdles could be overcome, it could be possible to produce PEI fibers in the 3 to 10 micrometer range.
Polyphenylene ether (PPE) resin and/or polybutylene terephthalate (PBT) resin fibers are used in many applications and composite structures that require various unique properties of the different resins to perform in the necessary environment. Many of these applications require the resins to be in a fiber size much smaller than currently achievable using conventional methods of fiber production at a reasonable throughput rate. This has been a barrier to the introduction and testing of many of these resins suitability for use in these applications. PPE and PBT resins have been converted down to 15 to 20 micrometers in diameter using the melt spinning process, but haven't been used in melt blowing processes.
Polycarbonate (PC) and PC copolymer fibers are used in many applications and composite structures that require various unique properties of the different resins to perform in the necessary environment. Many of these applications require the resins to be in a fiber size much smaller than currently achievable using conventional methods of fiber production at a reasonable throughput rate. This has been a barrier to the introduction and testing of many of these resins suitability for use in these applications. PC and PC Copolymers have been converted into fibers using the melt spinning process for some time. This is capable of producing fibers in the range of 10-20 micrometers. Melt blowing has also been used for some PC's producing fibers in the 1 to 10 micrometer range.
Electro-spinning of all of these resins is possible, but the cost of the resin and the slow throughput rate of this process have made this method unacceptable. Typical production rates for this process are in the 200 to 300 grams per hour, and 60 meters per minute line speed rates.
For the foregoing reasons, there is a need for PEI resins, Polyphenylene ether (PPE), such as NORYL™ resins or PPO™ resins, Polybutylene terephthalate (PBT) VALOX™ resins, and Polycarbonate (PC), and PC Copolymer LEXAN™ resins in nano-fiber form produced from a shear spinning process in applications, such as electrical paper, battery separator membranes, structural composites and filter papers.